JP2005228476A - Magnetic recording medium and magnetic storage apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat stability of written bits using a simple medium structure, to reduce medium noise, and to enable performing high density recording having high reliability without affecting the performance of a magnetic recording medium, in a magnetic recording medium and a magnetic storage apparatus. <P>SOLUTION: This medium has an underlayer consisting of a Cr alloy including Mo; an intermediate layer provided on the underlayer and consisting of a ferromagnetic material; a non-magnetic binding layer provided on the intermediate layer; and a magnetic layer provided on the non-magnetic binding layer, and the intermediate layer is constituted so that it is magnetization-reversed independently of the magnetic layer and functions as a ferry binding layer of which the magnetization direction is made anti-parallel to the magnetic layer in a non-magnetic field. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic recording medium and a magnetic storage device, and more particularly to a magnetic recording medium and a magnetic storage device suitable for high-density recording.

  The recording density of a horizontal magnetic recording medium such as a magnetic disk has increased remarkably due to the reduction of medium noise and the development of magnetoresistive heads and spin valve heads. A typical magnetic recording medium has a structure in which a substrate, an underlayer, a magnetic layer, and a protective layer are laminated in this order. The underlayer is made of Cr or a Cr-based alloy, and the magnetic layer is made of a Co-based alloy.

Various methods for reducing the medium noise have been proposed so far. For example, in Non-Patent Document 1 (Okamoto et al., “Rigid Disk Medium for 5 Gbit / in ² Recording”, AB-3, Intermag '96 Digest), an appropriate underlayer made of CrMo is used to form a magnetic layer. It has been proposed to reduce the particle size and size distribution of the magnetic layer by reducing the thickness. Patent Document 2 (US Pat. No. 5,693,426) proposes using an underlayer made of NiAl. Further, in Non-Patent Document 2 (Hosoe et al., “Experimental Study of Thermal Decay in High-Density Magnetic Recording Media”, IEEE Trans. Magn. Vol. 33, 1528 (1997), an underlayer made of CrTi is used. The underlayer as described above promotes in-plane orientation of the magnetic layer and increases the residual magnetization and the thermal stability of the bit, reduces the thickness of the magnetic layer, increases the resolution, or It has also been proposed to reduce the transition width between written bits, and to promote Cr segregation in a magnetic layer made of a CoCr alloy and reduce exchange coupling between grains.

However, as the magnetic layer grains become smaller and magnetically isolated from each other, the written bits become unstable due to demagnetizing fields and thermal activation that increase with linear density. Non-Patent Document 3 (Lu et al., "Thermal Instability at 10 Gbit / in ² Magnetic Recording", IEEE
In Trans. Magn. Vol. 30, 4230 (1994)), in a medium in which exchange coupling of each particle having a diameter of 10 nm, 400 kfci bits and a ratio of K _u V / k _B T˜60 is suppressed by micromagnetic simulation. It has been announced that it is susceptible to significant thermal decay. Here, _Ku is a magnetic anisotropy constant, V is an average volume of magnetic particles, k _B is a Boltzmann constant, and T is a temperature. The ratio _Ku V / k _B T is also referred to as a thermal stability coefficient.

Non-Patent Document 4 (Abarra et al., “Thermal Stability of Narrow Track Bits in a 5 Gbit / in ² Medium”, IEEE Trans. Magn. Vol. 33, 2995 (1997)) describes the exchange interaction between particles. Stabilization of the presence-written bit has been reported by annealed 200 kfci bit MFM (magnetic force microscopy) analysis of 5 Gbit / in ² CoCrPtTa / CrMo media. However, at a recording density of ²⁰ Gbit / in ² or more, further suppression of magnetic coupling between particles becomes essential.

  A reasonable solution to this has been to increase the magnetic anisotropy of the magnetic layer. However, to increase the magnetic anisotropy of the magnetic layer, a large load is applied to the write magnetic field of the head.

  The coercivity of a thermally unstable magnetic recording medium is described in Non-Patent Document 5 (He et al., “High Speed Switching in Magnetic Recording Media”, J. Magn. Magn. Mater. Vol.155, 6 ( 1996)), and non-patent document 6 (JH Richter, “Dynamic Coercivity Effects in Thin Film Media”, IEEE Trans. Magn. Vol. 34, 1540 (1997)). As the switch time decreases, it increases rapidly. This adversely affects the data rate. That is, how fast data can be written to the magnetic layer, and the magnetic field strength of the head necessary for reversing the magnetization of the magnetic particles increases rapidly as the switch time decreases.

On the other hand, as another method for improving the thermal stability, a method for increasing the orientation ratio of the magnetic layer by applying an appropriate texture treatment to the substrate under the magnetic layer has been proposed. For example, in the published non-patent document 7 (Akimoto et al., “Magnetic Relaxation in Thin Film Media as a Function of Orientation”, J. Magn. Magn. Mater. (1999)), it is effective by micromagnetic simulation. It has been reported that the KuV / kB T value increases with a slight increase in orientation. As a result, Non-Patent Document 8 (Abarra
et al., “The Effect of Orientation Ratio on the Dynamic Coercivity of Media for> 15 Gbit / in ² Recording”, EB-02, Intermag '99, Korea) Time dependency can be weakened, and overwrite performance can be improved.

Furthermore, a keeper magnetic recording medium for improving thermal stability has also been proposed. The keeper layer is composed of a soft magnetic layer. This soft magnetic layer is disposed above or below the magnetic layer. In many cases, a Cr magnetic insulating layer is provided between the soft magnetic layer and the magnetic layer. The soft magnetic layer reduces the demagnetizing field of the bits written in the magnetic layer. However, due to the coupling of the soft magnetic layer that is continuously exchange coupled with the magnetic recording layer, the purpose of decoupling particles in the magnetic layer (reducing exchange coupling between particles in the magnetic layer) cannot be achieved. As a result, medium noise increases.
US Pat. No. 5,693,426 Okamoto et al., “Rigid Disk Medium for 5 Gbit / in2 Recording”, AB-3, Intermag '96 Digest Hosoe et al., "Experimental Study of Thermal Decay in High-Density Magnetic Recording Media", IEEETrans. Magn. Vol. 33, 1528 (1997) Lu et al., "Thermal Instability at 10 Gbit / in2 Magnetic Recording", IEEETrans. Magn. Vol.30, 4230 (1994) Abarra et al., "Thermal Stability of Narrow Track Bits in a 5Gbit / in2 Medium", IEEE Trans. Magn. Vol.33, 2995 (1997) He et al., "HighSpeed Switching in Magnetic Recording Media", J. Magn. Magn. Mater.Vol.155, 6 (1996) JH Richter, "Dynamic Coercivity Effects in Thin FilmMedia", IEEE Trans. Magn. Vol.34, 1540 (1997) Akimoto et al., "Magnetic Relaxation in Thin Film Media as a Function of Orientation", J. Magn. Magn. Mater. (1999) Abarra et al., "The Effect of Orientation Ratio on the DynamicCoercivity of Media for> 15Gbit / in2 Recording", EB-02, Intermag '99, Korea

  Various methods for improving the thermal stability and reducing the medium noise have been proposed. However, in the proposed method, the thermal stability of the written bit cannot be significantly improved. For this reason, it is difficult to greatly reduce the medium noise. In addition, depending on the proposed method, there is a problem in that the performance of the magnetic recording medium is adversely affected as a countermeasure for reducing the medium noise.

  Specifically, in order to obtain a magnetic recording medium with high thermal stability, (i) increase the magnetic anisotropy constant Ku, (ii) decrease the temperature T, or (iii) particles of the magnetic layer Measures such as increasing the volume V can be considered. However, in the countermeasure (i), the coercive force increases and it becomes more difficult to write information in the magnetic layer. On the other hand, the measure (ii) is impractical considering that the operating temperature of a disk drive or the like may exceed 60 ° C., for example. Furthermore, the measure (iii) increases the medium noise as described above. Further, it is conceivable to increase the film thickness of the magnetic layer in place of the countermeasure (iii), but this method lowers the resolution.

  SUMMARY OF THE INVENTION Accordingly, it is a general object of the present invention to provide a new and useful magnetic recording medium and magnetic storage device that solve the above problems.

  A more specific object of the present invention is to use a simple media structure to improve the thermal stability of written bits, reduce media noise, and improve reliability without adversely affecting the performance of magnetic recording media. An object of the present invention is to provide a magnetic recording medium and a magnetic storage device that can perform high-density recording.

  Another object of the present invention is to provide an underlayer made of a Cr alloy containing Mo, an intermediate layer made of a ferromagnetic material provided on the underlayer, a nonmagnetic coupling layer provided on the intermediate layer, A magnetic layer provided on the magnetic coupling layer, and the intermediate layer functions as a ferri coupling layer whose magnetization is reversed independently of the magnetic layer and whose magnetization direction is antiparallel to the magnetic layer in the absence of a magnetic field. Another object of the present invention is to provide a magnetic recording medium.

  Still another object of the present invention includes an intermediate layer made of a ferromagnetic material, a nonmagnetic coupling layer provided on the intermediate layer, and a magnetic layer provided on the nonmagnetic coupling layer. Is characterized by reversing the magnetization independently of the magnetic layer and functioning as a ferri-coupling layer in which the magnetization direction is antiparallel to the magnetic layer in the absence of a magnetic field (when information is not applied with a head magnetic field). An object of the present invention is to provide a magnetic recording medium.

  The intermediate layer may be made of a material selected from a group of Co-based alloys having an hcp structure including CoCrTa and CoCrPtTa. In this case, the Cr composition of the intermediate layer may be 10 at% or more and 20 at% or less, the Ta composition may be 0.5 at% or more and 10 at% or less, and the Pt composition may be 10 at% or less.

  Another object of the present invention can also be achieved by a magnetic storage device comprising at least one magnetic recording medium as described above.

  Other objects and features of the present invention will be apparent from the description given below with reference to the drawings.

  According to the present invention, a simple medium structure is used to improve the thermal stability of written bits, to reduce medium noise, and to perform high-density recording with high reliability without adversely affecting the performance of magnetic recording media. Can be realized.

  Embodiments of a magnetic recording medium and a magnetic storage device according to the present invention will be described below with reference to the drawings.

  First, the operation principle of the present invention will be described.

  The present invention uses a plurality of layers having magnetic structures that are antiparallel to each other. For example, in SSP Parkin, “Systematic Variation of the Strength AND Oscillation Period of Indirect Magnetic Exchange Coupling though the 3d, 4d, AND 5d Transition Metals”, Phys. Rev. Lett. Vol. 67, 3598 (1991), Ru, Magnetic transition metals such as Co, Fe, and Ni that are coupled to the magnetic layer through a thin non-magnetic intermediate layer such as Rh are described. On the other hand, US Pat. No. 5,701,223 proposes a spin valve that uses the above-described layers as stacked pinning layers in order to stabilize the sensor.

  When the Ru or Rh layer provided between the two ferromagnetic layers has a specific thickness, the magnetization directions of the ferromagnetic layers can be parallel or antiparallel to each other. For example, in the case of a structure composed of two ferromagnetic layers having different film thicknesses and anti-parallel magnetization directions, the effective particle size of the magnetic recording medium can be increased without substantially affecting the resolution. The signal amplitude reproduced from such a magnetic recording medium decreases due to the magnetization in the reverse direction. For this, a layer having an appropriate film thickness and magnetization direction is further provided under the laminated magnetic layer structure. Thus, the influence of one layer can be counteracted. As a result, the signal amplitude reproduced from the magnetic recording medium can be increased and the effective particle volume can be increased. Therefore, a written bit with high thermal stability can be realized.

  The present invention improves the thermal stability of written bits by using a laminated ferrimagnetic structure in which the magnetic layer is exchange coupled in the opposite magnetization direction to the other ferromagnetic layers. The ferromagnetic layer or the laminated ferrimagnetic layer is composed of a magnetic layer made of particles with reduced exchange interaction between particles. That is, the present invention uses a ferrimagnetic multilayer structure having an exchange pinning ferromagnetic layer in order to improve the thermal stability performance of the magnetic recording medium.

  FIG. 1 is a sectional view showing an essential part of a first embodiment of a magnetic recording medium according to the present invention. The magnetic recording medium includes a nonmagnetic substrate 1, a first seed layer 2, a NiP layer 3, a second seed layer 4, an underlayer 5, a nonmagnetic intermediate layer 6, a ferromagnetic layer 7, a nonmagnetic coupling layer 8, and a magnetic layer. The layer 9, the protective layer 10, and the lubricating layer 11 have a structure in which they are stacked in this order as shown in FIG.

  For example, the nonmagnetic substrate 1 is made of Al, an Al alloy, or glass. The nonmagnetic substrate 1 may or may not be textured. The first seed layer 2 is made of Cr, for example, particularly when the nonmagnetic substrate 1 is made of glass. The NiP layer 3 may or may not be textured or oxidized on the surface. The second seed layer 4 is provided to improve the orientation of the (001) plane of the Cr-based underlayer 5. The second seed layer 4 is made of a suitable material similar to that of the first seed layer 2.

  When the magnetic recording medium is a magnetic disk, the texture processing applied to the nonmagnetic substrate 1 or the NiP layer 3 is performed along the circumferential direction of the disk, that is, the direction in which the track on the disk extends.

  The nonmagnetic intermediate layer 6 is formed by epitaxial growth of the ferromagnetic layers 7 to 9, reduction of the particle distribution width, and an anisotropic axis (easy magnetization axis) of the magnetic layer 9 along a plane parallel to the recording surface of the magnetic recording medium. ) To facilitate the orientation. The nonmagnetic intermediate layer 6 is made of an alloy having an hcp structure such as CoCr-M, and has a thickness selected in the range of 1 to 5 nm. Here, M = B, Cu, Mo, Nb, Ta, W or an alloy thereof.

  The ferromagnetic layer 7 is made of Co, Ni, Fe, a Co alloy, a Ni alloy, a Fe alloy, or the like. That is, a Co-based alloy containing CoCrTa, CoCrPt, and CoCrPt-M can be used for the ferromagnetic layer 7. Here, M = B, Cu, Mo, Nb, Ta, W or an alloy thereof. The ferromagnetic layer 7 has a thickness selected in the range of 2 to 10 nm. The nonmagnetic coupling layer 8 is made of Ru, Rh, Ir, Ru-based alloy, Rh-based alloy, Ir-based alloy or the like. For example, the nonmagnetic coupling layer 8 has a thickness selected in the range of 0.4 to 1.0 nm, and preferably has a thickness of about 0.6 to 0.8 nm. By selecting the film thickness of the nonmagnetic coupling layer 8 in such a range, the magnetization directions of the ferromagnetic layer 7 and the magnetic layer 9 are antiparallel to each other in the absence of a magnetic field. The ferromagnetic layer 7 and the nonmagnetic coupling layer 8 constitute an exchange layer structure.

  The magnetic layer 9 is made of Co or a Co-based alloy containing CoCrTa, CoCrPt, CoCrPt-M, or the like. Here, M = B, Cu, Mo, Nb, Ta, W or an alloy thereof. The magnetic layer 9 has a thickness selected in the range of 5 to 30 nm. Of course, it is needless to say that the magnetic layer 9 is not limited to a single layer structure and may have a multilayer structure.

  The protective layer 10 is made of C, for example. The lubricating layer 11 is made of an organic lubricant for using the magnetic recording medium with a magnetic transducer such as a spin valve head. The protective layer 10 and the lubricating layer 11 constitute a protective layer structure on the magnetic recording medium.

  Of course, the layer structure provided under the exchange layer structure is not limited to that shown in FIG. For example, the underlayer 5 is made of Cr or a Cr-based alloy and formed on the substrate 1 with a film thickness selected in the range of 5 to 40 nm, and the exchange layer structure may be provided on such an underlayer 5. good.

  Next, a description will be given of a second embodiment of the magnetic recording medium according to the present invention.

  FIG. 2 is a sectional view showing an essential part of a second embodiment of the magnetic recording medium according to the present invention. In the figure, the same parts as those in FIG.

  In the second embodiment of the magnetic recording medium, the exchange layer structure is composed of two nonmagnetic coupling layers 8 and 8-1 and two ferromagnetic layers 7 and 7-1 constituting a ferrimagnetic multilayer structure. By using such a structure, the magnetizations of the two nonmagnetic coupling layers 8 and 8-1 cancel each other without canceling a part of the magnetic layer 9, so that the effective magnetization and the signal can be increased. It becomes. As a result, the particle volume of the magnetic layer 9 and the thermal stability of the magnetization are effectively increased. As long as the orientation of the axis of easy magnetization of the recording layer is preferably maintained, an effective two-layer structure consisting of a pair of a ferromagnetic layer and a nonmagnetic layer can increase the effective particle volume.

  The ferromagnetic layer 7-1 is made of the same material as that of the ferromagnetic layer 7, and the film thickness is selected in the same range as the ferromagnetic layer 7. The nonmagnetic coupling layer 8-1 is made of the same material as the nonmagnetic coupling layer 8, and the film thickness is selected in the same range as the nonmagnetic coupling layer 8. Between the ferromagnetic layers 7 and 7-1, the c-axis is substantially along the in-plane direction, and the grains grow in a columnar shape.

  In this embodiment, the magnetic anisotropy of the ferromagnetic layer 7-1 is set to be stronger than the magnetic anisotropy of the ferromagnetic layer 7. However, the magnetic anisotropy of the ferromagnetic layer 7-1 may be stronger or weaker than the magnetic anisotropy of the ferromagnetic layer 7, or may be set to be the same. In short, it is sufficient that the magnetic anisotropy of the ferromagnetic layer 7 is weaker than that of the upper and lower layers 9 and 7-1.

  The product of the residual magnetization and film thickness of the ferromagnetic layer 7 is set smaller than the product of the residual magnetization and film thickness of the ferromagnetic layer 7-1.

  FIG. 3 is a diagram showing in-plane magnetic characteristics of a single CoPt layer having a thickness of 10 nm formed on a Si substrate. In FIG. 3, the vertical axis represents magnetization (emu) and the horizontal axis represents coercivity (Oe). A conventional magnetic recording medium exhibits characteristics as shown in FIG.

  FIG. 4 is a diagram showing in-plane magnetic characteristics of two CoPt layers separated by a Ru layer having a thickness of 0.8 nm as in the first embodiment of the recording medium. In FIG. 4, the vertical axis represents residual magnetization (Gauss), and the horizontal axis represents coercivity (Oe). As can be seen from FIG. 4, the loop is shifted in the vicinity of the coercive force, and antiferromagnetic coupling occurs. FIG. 5 is a diagram showing in-plane magnetic characteristics of two CoPt layers separated by a Ru layer having a thickness of 1.4 nm. In FIG. 5, the vertical axis represents remanent magnetization (emu), and the horizontal axis represents coercivity (Oe). As can be seen from FIG. 5, the magnetization directions of the two CoPt layers are parallel.

  FIG. 6 is a diagram showing in-plane magnetic characteristics of two CoCrPt layers separated by a Ru layer having a thickness of 0.8 nm as in the second embodiment. In FIG. 6, the vertical axis represents remanent magnetization (emu / cc), and the horizontal axis represents coercivity (Oe). As can be seen from FIG. 6, the loop is shifted in the vicinity of the coercive force, and antiferromagnetic coupling occurs.

  3 and 4, it can be seen that antiparallel coupling can be obtained by providing the exchange layer structure. Further, as can be seen by comparing FIG. 5 with FIGS. 4 and 6, the film thickness of the nonmagnetic coupling layer 8 is preferably in the range of 0.4 to 0.9 nm in order to obtain antiparallel coupling. Selected.

  Therefore, according to the first and second embodiments of the magnetic recording medium, the effective particle volume is reduced without sacrificing resolution by exchange coupling via the nonmagnetic coupling layer between the magnetic layer and the ferromagnetic layer. Can be increased. That is, the apparent film thickness of the magnetic layer can be increased when viewed from the particle volume so that a medium having good thermal stability can be realized. Further, since the reproduction output from the lower magnetic layer is canceled, the effective magnetic layer thickness does not change. For this reason, although the apparent thickness of the magnetic layer increases, the effective thickness of the magnetic layer can be reduced without change, so that high resolution that cannot be obtained with a thick medium can be obtained. As a result, it is possible to obtain a magnetic recording medium with reduced medium noise and improved thermal stability.

  Next, a description will be given of a third embodiment of the magnetic recording medium according to the present invention.

  FIG. 7 is a sectional view showing an essential part of a third embodiment of the magnetic recording medium according to the present invention. In the figure, the same parts as those in FIG.

  In the present embodiment, the nonmagnetic substrate 1 is made of Al having a NiP plating layer (not shown) formed on the surface, and the NiP plating layer is textured or oxidized. It has been subjected. The nonmagnetic substrate 1 may be made of glass, tempered glass, or crystallized glass having a surface on which an orientation adjusting layer such as NiP, CrP, or NiAl is formed.

The underlayer 5 made of a Cr-based alloy has a two-layer structure. Specifically, the underlayer 5 includes a first underlayer 5-1 made of Cr having a thickness of 3 nm and a second underlayer 5-2 made of CrMo ₂₅ having a thickness of 3 nm. The nonmagnetic intermediate layer 6 made of a Co-based alloy is made of CoCr ₁₃ Ta ₅ having a thickness of 1 nm. The ferromagnetic layer 7 is made of CoCr ₂₀ Pt ₁₀ B ₆ Cu ₄ having a thickness of 5 nm. The nonmagnetic coupling layer 8 is made of Ru having a thickness of 0.6 nm. The magnetic layer 9 is made of CoCr ₂₀ Pt ₁₀ B ₆ Cu ₄ having a film thickness of 12 nm and the same composition as the ferromagnetic layer 7.

  Next, a description will be given of a fourth embodiment of the magnetic recording medium according to the present invention.

  FIG. 8 is a sectional view showing an essential part of a fourth embodiment of the magnetic recording medium according to the present invention. In the figure, the same parts as those in FIG.

In this embodiment, a ferromagnetic intermediate layer 31 shown in FIG. 8 is provided instead of the intermediate layer 6 and the ferromagnetic layer 7 shown in FIG. The intermediate layer 31 made of a Co-based alloy is made of CoCr ₁₃ Ta ₅ having a thickness of 3 nm. The compositions and film thicknesses of the other layers 5, 8, and 9 are the same as those in FIG. The magnetic recording medium layers 5-1, 5-2, 31, 8, and 9 are sequentially sputtered on the nonmagnetic substrate 1 after the nonmagnetic substrate 1 is cleaned and heated to 220 ° C. by a magnetron sputtering apparatus. Can be formed.

  FIG. 9 is a sectional view showing an essential part of a fifth embodiment of the magnetic recording medium according to the present invention. In the figure, the same parts as those in FIG.

In this embodiment, an intermediate layer 32 shown in FIG. 9 is provided instead of the intermediate layer 31 shown in FIG. The intermediate layer 32 made of a Co-based alloy is made of CoCr ₂₀ Pt ₁₀ B ₆ Cu ₄ having the same composition as the magnetic layer 9 having a thickness of 3 nm.

  10, FIG. 11 and FIG. 12 are diagrams showing the hysteresis loops of the third embodiment shown in FIG. 7, the fourth embodiment shown in FIG. 8, and the fifth embodiment shown in FIG. 10 to 12, the vertical axis represents magnetization in arbitrary units, and the horizontal axis represents magnetic field (Oe).

  As can be seen from FIGS. 10 to 12, in the third to fifth examples, it was confirmed that the magnetization suddenly changed in the vicinity of the magnetic field of about 300 to 500 Oe. This is because the lower ferromagnetic layer 7 or the intermediate layers 31 and 32 function as a ferricouple layer due to a magnetic field, and the magnetization is reversed independently of the upper magnetic layer 9, so that the magnetic layer 9 and the ferricouple layer (ferromagnetic layer 7 Or, it is shown that the magnetization directions are antiparallel to the intermediate layers 31 and 32).

FIG. 13 is a diagram showing the electromagnetic conversion characteristics of the third to fifth embodiments. In the figure, the vertical axis represents the signal-to-noise (S / N) ratio (dB). The S / N ratio shown in the figure was obtained by determining the ratio of the reproduction output at 63.3 kFCI and the medium noise at 357.3 kFCI in dB using the following equation.

S / N ratio (dB) = 20 log (S / N); S, N (μVrms)

As can be seen from FIG. 13, it was confirmed that the S / N ratio was substantially the same in the third example and the fourth example, and was higher than the S / N ratio in the fifth example. In general, the CoCr ₁₃ Ta ₅ magnetic layer generates more media noise than the CoCr ₂₀ Pt ₁₀ B ₆ Cu ₄ magnetic layer, but the Ferri coupling layer (intermediate layer 31) of the fourth embodiment shown in FIG. In this case, it was confirmed that the medium noise of the entire magnetic recording medium was not affected. Therefore, in the third embodiment shown in FIG. 7, the intermediate layer 31 made of the same material as the intermediate layer 6 used for the purpose of promoting the in-plane orientation of the magnetic layer 9 is changed to the fourth embodiment shown in FIG. Then, it can be used as a ferribonding layer. In addition, a medium-noisy material is thermally stable because the exchange interaction between magnetic particles is not broken.

  Therefore, by providing the intermediate layer 31 as the ferrimagnetic coupling layer as in the fourth embodiment, the in-plane orientation of the magnetic layer 9 is improved, and the heat of the bits written on the magnetic recording medium without causing a medium noise source. Stability can be improved. Furthermore, in the fourth embodiment, the structure can be reduced by one layer compared to the third embodiment, so that the manufacturing process of the magnetic recording medium can be reduced and the manufacturing cost of the magnetic recording medium can be reduced.

  In the fourth embodiment, the intermediate layer 31 may be made of a material selected from a group of Co-based alloys having an hcp structure such as CoCrTa and CoCrPtTa, and the film thickness is preferably about 5 nm or less. . In the intermediate layer 31 made of a Co-based alloy, it is preferable that the Cr composition is 10 at% or more and 20 at% or less, the Ta composition is 0.5 at% or more and 10 at% or less, and the Pt composition is 10 at% or less. The nonmagnetic coupling layer 8 is not limited to Ru, and may be made of a material selected from the group consisting of Ru, Rh, Ir, Cu, Cr, or alloys thereof. Further, the magnetic layer 9 may be made of a material selected from the group consisting of Co, Ni, Fe, Fe alloys, Ni alloys, and Co alloys including CoCrTa, CoCrPt, CoCrPt-M, M = B, Cu, Mo, Nb, Ta, W or an alloy thereof may be used.

  Next, an embodiment of a magnetic storage device according to the present invention will be described with reference to FIGS. FIG. 14 is a cross-sectional view showing the main part of one embodiment of the magnetic memory device, and FIG. 15 is a plan view showing the main part of one embodiment of the magnetic memory device.

  As shown in FIG. 14 and FIG. 15, the magnetic storage device is generally composed of a housing 13. In the housing 13, a motor 14, a hub 15, a plurality of magnetic recording media 16, a plurality of recording / reproducing heads 17, a plurality of suspensions 18, a plurality of arms 19, and an actuator unit 20 are provided. The magnetic recording medium 16 is attached to a hub 15 that is rotated by a motor 14. The recording / reproducing head 17 includes a reproducing head such as an MR head or a GMR head, and a recording head such as an inductive head. Each recording / reproducing head 17 is attached to the tip of a corresponding arm 19 via a suspension 18. The arm 19 is driven by the actuator unit 20. The basic configuration itself of this magnetic storage device is well known, and detailed description thereof is omitted in this specification.

  This embodiment of the magnetic storage device is characterized by the magnetic recording medium 16. Each magnetic recording medium 16 has the structure of any one of the first to fifth embodiments of the magnetic recording medium described with reference to FIGS. 1, 2, and 7 to 9. Of course, the number of magnetic recording media 16 is not limited to three, and may be one, two, or four or more.

  The basic configuration of the magnetic storage device is not limited to that shown in FIGS. The magnetic recording medium used in the present invention is not limited to a magnetic disk.

  Although the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the present invention.

In addition, this invention also includes the invention attached to the following.
(Supplementary note 1) An intermediate layer made of a ferromagnetic material;
A nonmagnetic coupling layer provided on the intermediate layer;
A magnetic layer provided on the nonmagnetic coupling layer,
The magnetic recording medium, wherein the intermediate layer functions as a ferri-coupled layer whose magnetization is reversed independently of the magnetic layer and whose magnetization direction is antiparallel to the magnetic layer in the absence of a magnetic field.
(Supplementary note 2) The magnetic recording medium according to supplementary note 1, wherein the intermediate layer is made of a material selected from a group of Co-based alloys having an hcp structure containing CoCrTa and CoCrPtTa.
(Additional remark 3) The Cr composition of the said intermediate | middle layer is 10 at% or more and 20 at% or less, Ta composition is 0.5 at% or more and 10 at% or less, Pt composition is 10 at% or less, The additional description 2 characterized by the above-mentioned. Magnetic recording medium.
(Additional remark 4) The said nonmagnetic coupling layer consists of material selected from the group which consists of Ru, Rh, Ir, Cu, Cr, or these alloys, Any one of Additional remark 1-3 Magnetic recording media.
(Supplementary Note 5) The magnetic layer is made of a material selected from the group consisting of Co, Ni, Fe, Fe alloys, Ni alloys, and Co alloys including CoCrTa, CoCrPt, CoCrPt-M, and M = B The magnetic recording medium according to any one of appendices 1 to 4, wherein the magnetic recording medium is Cu, Mo, Nb, Ta, W, or an alloy thereof.
(Supplementary note 6) The magnetic recording medium according to any one of Supplementary notes 1 to 5, wherein the nonmagnetic coupling layer is in direct contact with both the ferromagnetic intermediate layer and the magnetic layer.
(Appendix 7) an underlayer provided under the ferromagnetic intermediate layer;
A substrate provided under the base layer,
The magnetic recording medium according to any one of appendices 1 to 6, wherein the surface of the substrate is textured or oxidized.
(Supplementary note 8) an underlayer provided under the ferromagnetic intermediate layer;
A substrate provided under the base layer,
7. The magnetic recording medium according to any one of appendices 1 to 6, wherein an orientation adjustment layer is provided on the surface of the substrate.
(Appendix 9) A magnetic storage device comprising at least one magnetic recording medium according to any one of appendices 1 to 8.
(Supplementary Note 10) An underlayer made of a Cr alloy containing Mo,
An intermediate layer made of a ferromagnetic material provided on the underlayer;
A nonmagnetic coupling layer provided on the intermediate layer;
A magnetic layer provided on the nonmagnetic coupling layer,
The magnetic recording medium, wherein the intermediate layer functions as a ferri-coupled layer whose magnetization is reversed independently of the magnetic layer and whose magnetization direction is antiparallel to the magnetic layer in the absence of a magnetic field.
(Supplementary note 11) The magnetic recording medium according to supplementary note 10, wherein the magnetic layer is made of a material containing Pt.
(Supplementary note 12) The magnetic recording medium according to supplementary note 10, wherein the magnetic layer is made of CoCrPt or CoCrPt-M and is M = B, Cu, Mo, Nb, Ta, W, or an alloy thereof.
(Additional remark 13) The board | substrate provided under the said base layer,
The magnetic recording medium according to any one of appendices 10 to 12, further comprising an orientation adjustment layer provided on the substrate.
(Supplementary note 14) A magnetic storage device comprising at least one magnetic recording medium according to any one of supplementary notes 10 to 13.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the present invention.

It is sectional drawing which shows the principal part of 1st Example of the magnetic recording medium which becomes this invention. It is sectional drawing which shows the principal part of 2nd Example of the magnetic recording medium which becomes this invention. It is a figure which shows the in-plane magnetic characteristic of a single CoPt layer with a film thickness of 10 nm formed on the Si substrate. It is a figure which shows the in-plane magnetic characteristic of two CoPt layers isolate | separated by the Ru layer whose film thickness is 0.8 nm. It is a figure which shows the in-plane magnetic characteristic of two CoPt layers isolate | separated by the Ru layer whose film thickness is 1.4 nm. It is a figure which shows the in-plane magnetic characteristic of two CoCrPt layers isolate | separated by the Ru layer whose film thickness is 0.8 nm. It is sectional drawing which shows the principal part of 3rd Example of the magnetic recording medium which becomes this invention. It is sectional drawing which shows the principal part of 4th Example of the magnetic recording medium which becomes this invention. It is sectional drawing which shows the principal part of 5th Example of the magnetic recording medium which becomes this invention. It is a figure which shows the hysteresis loop of 3rd Example. It is a figure which shows the hysteresis loop of 4th Example. It is a figure which shows the hysteresis loop of 5th Example. It is a figure which shows the electromagnetic conversion characteristic of 3rd Example-5th Example. It is sectional drawing which shows the principal part of one Example of the magnetic memory device which becomes this invention. It is a top view which shows the principal part of one Example of a magnetic memory device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 4 Seed layer 3 NiP layer 5 Underlayer 6 Nonmagnetic intermediate layer 7 Ferromagnetic layer 8 Nonmagnetic coupling layer 9 Magnetic layer

Claims (5)

An underlayer made of a Cr alloy containing Mo;
An intermediate layer made of a ferromagnetic material provided on the underlayer;
A nonmagnetic coupling layer provided on the intermediate layer;
A magnetic layer provided on the nonmagnetic coupling layer,
The magnetic recording medium, wherein the intermediate layer functions as a ferri-coupled layer whose magnetization is reversed independently of the magnetic layer and whose magnetization direction is antiparallel to the magnetic layer in the absence of a magnetic field.   2. The magnetic recording medium according to claim 1, wherein the magnetic layer is made of a material containing Pt.   2. The magnetic recording medium according to claim 1, wherein the magnetic layer is made of CoCrPt or CoCrPt-M, and M = B, Cu, Mo, Nb, Ta, W, or an alloy thereof. A substrate provided under the underlayer;
The magnetic recording medium according to claim 1, further comprising an orientation adjustment layer provided on the substrate. A magnetic storage device comprising at least one magnetic recording medium according to claim 1.

Images